About Me

My photo
Spofford, New Hampshire, United States
Jeff Newcomer had been a physician practicing in New Hampshire and Vermont for over 30 years. Over that time, as a member of the Conservation Commission in his home of Chesterfield New Hampshire, he has used his photography to promote the protection and appreciation of the town's wild lands. In recent years he has been transitioning his focus from medicine to photography, writing and teaching. Jeff enjoys photographing throughout New England, but has concentrated on the Monadnock Region and southern Vermont and has had a long term artistic relationship with Mount Monadnock. He is a featured artist in a number of local galleries and his work is often seen in regional print, web publications and in business installations throughout the country. For years Jeff has published a calendar celebrating the beauty of The New England country-side in all seasons. All of the proceeds from his New England Reflections Calendar have gone to support the Pulmonary Rehabilitation Program at the Cheshire Medical Center. Jeff has a strong commitment to sharing his excitement about the special beauty of our region and publishes a blog about photography in New England.

Sunday, February 23, 2014

Hand-Held Focus Stacking

Snow Peak, Mount Monadnock, Marlborough, NH
Using Auto-Focus Points to Hold the Frame

This week I wanted to share a simple technique to obtain multiple (or at least two) images for focus stacking while hand-holding the camera.

Focus Stacking
I have previously discuss in considerable detail the technique of focus stacking to achieve deep depth of field.  This approach

requires multiple images focused at different planes of the scene which are then combined in post processing to achieve sharpness throughout.  A key requirement of the technique is that the images all be framed to match when aligned in the computer.  With sophisticated software, such as Photoshop, the match does not have to be perfect, but typically this is best achieved with the camera locked down on a tripod.  It can be quite challenging to manually vary focus while trying to hand-hold the framing perfectly constant.  This is where my camera's auto focus points can come to the rescue.

I have never been a big fan of auto-focus for my landscape
Hibernation, Pomfret, Vt.  Two focus planes.
photography.  Even as the technology has improved, I tend to prefer to assure sharpness by manually focusing, often on a tripod and, in poor light frequently, using the Live View Screen.  But when I am faced with a scene which contains a discrete foreground and distant background,  I can often get good results with a two image stack, one focused on the foreground detail and the other on the background.  This is the situation where auto-focus can save me the chore of getting out my tripod, if I have it on hand.

Mount Monadnock
Most photographers are familiar with the technique of holding the shutter down half-way to lock focus on a part of the scene and then
recomposing for the final shot.  This is most frequently used when focusing a subject that is off center, but the same technique can be used to grab a couple of images for a simple focus stack.  In the example of Mount Monadnock shot from Marlborough, New Hampshire, I locked focus on the detail of the fence and then re framed to include the distant mountain.  The first image caught the fence in clear focus and then without moving the camera I locked focus on mighty Monadnock and shot again.  As I shot the first image I carefully noted the position of the central focus point square to assist in close alignment of the second image.  In more complicated situations, fully sharp focus stacking can require more than two images, but in bright light, when I can stop down, two are often enough to get good results, especially when there are just two discrete planes of interest. 

Canon 5D Mark II Focus points

Mill Ice, Harrisville, New Hampshire
My Canon 5D Mark II has 9 focus points displayed on the screen, but only the central square is a cross sensor, vertical and horizontal, and therefore the most accurate.  When possible I try to use the central point for focus stacking but there are many times when the central point aligns with neither the foreground or background in my desired composition.  Faced with this situation I can usually find one of the other focus points that will provide the coverage I need.  In my image of the frozen mill pond in Harrisville, New Hampshire, I angled the camera down to using the top focus point to lock in the sharpness of the foreground ice and then recomposed.  In my second image, the focus point was in perfect position to catch the iconic Harrisville Public Library. 

Mill Freeze

Using one of the 8 peripheral focus points can reduce the reliability of the auto-focus, especially in dim light or low contrast. To help, I have switched my focus lock from the shutter to a button on the back of the camera that doesn't require continuous pressure to maintain the focus.  In the mill pond image, I could lock the foreground focus with the central point and then switch to the upper point ready for when I refocused on the background.  Not all cameras can switch the focus button. The directions for mine were buried in an obscure corner of my manual, but, with practice, the ability to lock focus without having to hold the shutter down, works well for me in most situations.

Focus Button on Back of the Camera

Ashuelot River, Keene, NH,
Multiple Focus Planes

The trick with this technique is to hold the camera steady as you re-press the shutter and to learn how to move the focus point around the screen.  I have gotten good enough that I will occasionally try to move the focus point within the screen to catch more than just two images for stacking.  The more manipulations I try, the harder it is to maintain the frame, but Photoshop can do some amazing things with auto-alignment.  Still it is about at this time that I grab for the tripod.

The speed and accuracy of auto-focus in modern cameras is amazing and improving all the time.  I still like to use manual focus in many landscape situation but it is important to understand your camera's focusing capabilities and to use them when the time is right.

Jeffrey Newcomer

1 comment: